Increase of intracerebral pressure (ICP) during laparoscopic surgery has known to be associated with positional changes. Optic nerve sheath diameter (ONSD) has correlation with ICP and ultrasonographic measurement of optic nerve sheath diameter (ONSD) is known to be a noninvasive and rapidly applicable technique for evaluating ICP. The aim of this study is to investigate the change of ONSD according to the positional change during laparoscopic surgery.

Patients were placed in the supine position with their eyes closed, and a thick gel layer was applied to the closed upper eyelid. The 7.5-MHz linear probe was placed on the gel without excessive pressure and adjusted to the proper angle for displaying the entry of the optic nerve into the globe. The intensity of the ultrasound was adjusted to display optimal contrast between the retrobulbar echogenic fat tissue and the vertical hypoechoic band. An ultrasound beam was focused on the retrobulbar area (4 cm deep) using the lowest possible acoustic power that could measure ONSD. The ONSD was measured 3 mm behind the optic disc. Measurements were performed in the transverse and sagittal planes of both eyes, and the final ONSD value was calculated by averaging 4 measured values.

Procedure: Mechanical ventilation

After tracheal intubation, the lungs of the patients were then ventilated with oxygen in air (1:2) using a tidal volume of 8-10 mL/kg and a respiratory rate of 10-12/min, and the ventilation rate was adjusted to maintain the end-tidal carbon dioxide partial pressure between 35 and 40 mmHg and peak inspiratory pressure below 30 cmH2O.

Procedure: Trendelenburg position - 30 degree

Trendelenburg position - 30 degree

Experimental: Group 2

Drug: Desflurane Anesthesia with desflurane in both Group 1 and Group 2 - adjust MAC to maintain BIS between 40-60

Patients were placed in the supine position with their eyes closed, and a thick gel layer was applied to the closed upper eyelid. The 7.5-MHz linear probe was placed on the gel without excessive pressure and adjusted to the proper angle for displaying the entry of the optic nerve into the globe. The intensity of the ultrasound was adjusted to display optimal contrast between the retrobulbar echogenic fat tissue and the vertical hypoechoic band. An ultrasound beam was focused on the retrobulbar area (4 cm deep) using the lowest possible acoustic power that could measure ONSD. The ONSD was measured 3 mm behind the optic disc. Measurements were performed in the transverse and sagittal planes of both eyes, and the final ONSD value was calculated by averaging 4 measured values.

Procedure: Mechanical ventilation

After tracheal intubation, the lungs of the patients were then ventilated with oxygen in air (1:2) using a tidal volume of 8-10 mL/kg and a respiratory rate of 10-12/min, and the ventilation rate was adjusted to maintain the end-tidal carbon dioxide partial pressure between 35 and 40 mmHg and peak inspiratory pressure below 30 cmH2O.

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Please refer to this study by its ClinicalTrials.gov identifier: NCT01937104

Locations

Korea, Republic of

Chosun University Hospital

Gwangju, Donggu, Korea, Republic of, 501-717

Sponsors and Collaborators

Chosun University Hospital

Investigators

Study Chair:

Ki Tae Jung, M.D.

Department of Anesthesiology and Pain medicine School of Medicine, Chosun University